Docker build/run/exec all of a sudden giving "[8] System error: no such file or directory"

E.g.

$ docker run -it debian:jessie
no such file or directory
Error response from daemon: Cannot start container e6c2c388d4902555a1897f28e3c0d5e6ef49cc228a604910fa481d86df51003a: [8] System error: no such file or directory

This system was working fine ~24hrs ago then all of sudden this started happening. A few containers which were running before this started happening seem to be running OK (but I can’t exec into them). This is a server running in production so while the currently running containers seem fine I’m very apt to fix this without having to take the server down. Any ideas how I can fix/debug what’s happening?

$ docker info
Containers: 6
Images: 377
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 391
 Dirperm1 Supported: true
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.19.0-31-generic
Operating System: Ubuntu 14.04.3 LTS
CPUs: 32
Total Memory: 251.9 GiB
Name: darkenergy
ID: HFOU:WMAG:6J3D:JLDB:LXBS:62C4:A7PY:RL5A:CP3V:ARO3:BGVC:DNXX
WARNING: No swap limit support

$ docker version
Client:
 Version:      1.8.3
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   f4bf5c7
 Built:        Mon Oct 12 05:37:18 UTC 2015
 OS/Arch:      linux/amd64

Server:
 Version:      1.8.3
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   f4bf5c7
 Built:        Mon Oct 12 05:37:18 UTC 2015
 OS/Arch:      linux/amd64

$ uname -a
Linux darkenergy 3.19.0-31-generic #36~14.04.1-Ubuntu SMP Thu Oct 8 10:21:08 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Looks like this was caused by apparmor being turned off. Turning it back on fixed everything without need for any restart.